According to the physical phenomena of atmospheric channels and wave propagation, performance of wireless communication system can be optimized by simply adjusting its natural parameters. This way is economically more favorable than consuming more power or using additional processing techniques. In this paper for the first time an optimization problem is developed on the performance of a free-space optical multiinput multi-output (FSO-MIMO) communication system. Also it is the first time that optimization of FSO system is developed under saturated atmospheric turbulence. In order to get closer to the actual results, the effect of pointing error is taken into considerations. Assuming MPSK, DPSK modulation schemes, new closed-form expressions are derived for Bit Error Rate (BER) and outage probability (Pout) of the proposed structure. Furthermore, an optimization problem is developed taking into account the equivalent beam waist as variable parameter, and BER as objective function, there is no constraint in this system. Obtained results can be a useful outcome for FSO-MIMO system designers in order to mitigate effects of pointing error as well as atmospheric turbulence and thus achieve optimum performance.

Keywords